340 pistons in a 360?

So, I have heard of a few guys doing this in the old days, using 340 pistons in a 360, I think they called it the Hoover engine. Anyway, I have a nice set of 340 standard-bore pistons laying around (I think, more on that in the second question), and a 360 that's itching for 'em. I was going to have the entire rotating assembly internally balanced anyway. So, besides the .040 overbore, anyone know how I'd go about this, and what issues I might face?
Now, I was just TOLD they were 340 pistons when I bought them at the swap, but how do I check and make sure? What are the differences? Maybe the guy sold me 360 stuff instead, it's happened to me before.
Author: admin